Not sure which forum to post this question in, but hoping someone here will recognize this problem.

There is a kind of web embedded with what looks like wood dust particles, located along the wood frame that surrounds my brick fireplace. I can wipe it away, no problem. In fact I've done that before, but it eventually shows up again.

What is causing it? I don't see any insects in or around it. Is it a sign of termites or wood/carpenter ants or what? If you CAN identify it, any suggestions for what to do?